Data-poor Fisheries Assessment

More than 90% of global fisheries are considered too small or data-poor for assessment with existing quantitative assessment models. With a series of groundbreaking studies, some still being published, Dr Prince has established fisheries can be assessed just with simple size studies slashing assessment costs by $100,000 to $million per stock.

The approach estimates the rate of spawning relative to unfished levels (spawning per recruit – SPR) rather than biomass trends, and incrementally adjusts fishing pressure to discover catch levels that stabilize stocks at management targets. Requiring only simple size studies the technique makes $5000 stock assessments possible, reducing a major impediment for data-poor fisheries. Serendipitously the new approach easily incorporates the management effects of Marine Protected Areas and facilitates implementing the Risk-Catch-Cost framework to fisheries management.

Funded by the David & Lucille Packard Foundation and The Nature Conservancy Dr Prince is working with the Marine Stewardship Council to establish a new certifiable standard for data-poor assessment, which they are implementing in case studies fisheries in every ocean basin.


Abalone Divers, Western Victoria, Australia

Since 2002 Dr Prince has developed a methodology for reef scale assessment and management for the Western Abalone Divers Association (WADA).

Building on an idea given to him by a Western Australian abalone diver, Dr Prince taught the abalone divers how to visually assess their own abalone reefs and facilitated workshops for WADA which assessed and developed management plans for each reef. Catch targets and size limits are now implemented by WADA at the scale of abalone reefs, below the scale of the government’s zonal assessment model. Regional Total Allowable Catches are being set on the locally assessed capacity of each reef and are lower than the level zonal assessment models suggest is sustainable. Supported by Australian Commonwealth Government R&D funding in 2005 this new form of bottom-up assessment and management for the Victorian abalone fishery has been incorporated into the statutory Fisheries Management Plan.

Dr Prince has Australian Commonwealth Government R&D funding in 2011/12 to trial his newly developed technique for empirically estimating SPR at size, to estimate size targets for catch composition data collected from each reef by WADA divers.


Santa Barbara Fisheries, California

California is a US state the size of most industrialized nations, home of a government facing a budget crisis and third world fisheries. Much of the theory behind using Marine Protected Areas (MPAs) is a reaction to the ‘scorched earth’ of Californian fishing grounds.

Dr Prince was introduced originally to the port of Santa Barbara and academics at the Bren School, UCSB by the now retired John Richards of California Sea Grants in 2001.

Over the years, Biospherics has bridged occasional consultancies from industry associations, Environmental Defense Fund, Californian Depart. Fish & Game and the University California, Santa Barbara, and Dr Prince has managed to build a network of co-operative relationships around the port of Santa Barbara interested in co-developing new approaches to data-poor fisheries. The Commercial Fishermen of Santa Barbara’s Association (CFSB) has a newly elected first female president in Stephanie Mutz and a strong group of industry leaders interested in working collaboratively with Dr Prince and Bren School academics Profs. Steve Gaines, Chris Costello, Sarah Lester and Hunter Lenihan, and students Jono Wilson, Sarah Valencia and Matt Kay working across the complete spectrum of the port’s main species; lobster, sea urchin and rockfish.

Sustainable Seafood Assesment (ACF)

The Australian Conservation Foundation (ACF) initiated a sustainable seafood assessment program for Australian wild caught and cultured seafood products in 2010.

The core of the program is an assessment process that ACF developed and implemented with a team of leading Australian marine scientists. The ACF and its Science Reference Panel had several key objectives when developing the assessment criteria and process. These were:

• independent, transparent and scientifically rigorous with quality benchmarks;
• outcomes based, time and cost effective and applicable to both wild catch and farmed seafood products;
• designed to provide for collaborative engagement with the seafood industry.

To ensure that the assessment process and decision-making of the Science Reference Panel (SRP) is independent of environment organisations, industry and government, ACF invited the University of Technology, Sydney (UTS), one of Australia’s leading tertiary education providers, to host the Panel and the Program.

On the basis of his broad independent experience with Australian fisheries Dr Prince was been a founding member of the Science Reference Panel that developed the assessment framework for the ACF and began rating seafood for restaurants in 2010.

South Australian Rock Lobster Fishery Review

The South Australian Rock Lobster Fishery has landed approximately 2,000t per annum of Jasus edwardsii and is one of that state’s most valuable fisheries. In 2010 the industry based South Australian Rock Lobster Advisory Council, and the state fisheries management agency PIRSA, selected Dr Prince and Prof. Ray Hilborn, University of Washington, to conduct parallel reviews of management plans and harvest strategy, and of the science and assessment program.

Since management with Individually Transferable Quota (commonly called Catch Shares in North America), the fishermen have been changing the way they fish. Prior to this form of management the fishers competed for access to high catch rate areas. Now they accept lower catch rates close to home ports, because when fuel costs are taken into account the return per kilo of quota filled, is better close to home. The fisheries data being collected, analyzed and use in a harvest strategy to set Total Allowable Catches are coarse scale and they have become very negative. Nothing beats good spatially explicit data. So the consultants reports extolled the virtue of collecting good spatially explicit data on catch, effort and size, and proposed a simple harvest strategy framework to set catch levels at finer scales.

Benthic Impact Study, Cultured Pearls

The premium pearl in the world, South Sea Pearls are cultured along the remote tropical Kimberley coastline of Western Australia. The Pearl Producer’s of Australia (PPA) pride themselves on their low impact culture techniques, but find themselves under increasing pressure to prove their credentials with independent scientific studies.

Dr Prince worked with the PPA to initiate, commission, supervise and facilitate a study by independent researchers from the University of Newcastle, into the potential for benthic impacts under pearl leases of long standing. Several of the oldest (50 years+) most intensively used leases were selected and benthic sediments and fauna benthos compared over several years between these sites between them and nearby control sites.

In addition to identifying many new species the study found the Kimberely sediments are incredibly diverse and seasonal cycling is dynamic. Despite being possibly the most exhaustive study of its type published, the study could find no impact that could be attributed to the heavily used lease areas. Undoubtedly due to the low stock densities compared the extreme tidal fluxing of nutrient and sediments through the leases. On this basis the PPA recommended against members undertaking the expense and risk of benthic monitoring within each farm’s Environmental Management System, but recommending repeating this type of targeted study periodically, or if culture techniques change.

Tasman Sea Tropical Tuna

In 2007 the Minister of Fisheries for the Commonwealth of Australia directed all Commonwealth managed fisheries should be managed with quantitative Harvest Strategies (HS); computerized decision rules using pre-agreed data to adjust catch levels. A mechanism for setting catch levels was needed immediately but international assessments would take decades to develop and of doubtful accuracy for the peripheral Tasman & Coral Sea stocks of tuna and billfish. Dr Prince was requested to participate on the Harvest Strategy Working Group established for the Eastern Tuna and Billfish Fishery.

Dr Prince designed the Spawning Per Recruit (SPR) Decision Tree using the logic of Virtual Population Analysis (VPA) to assess trends in size and catch rate data without reliance on quantitative population models. Harvest Strategy Evaluation by CSIRO confirmed the utility of the approach and found that the HS usefully becomes more precautionary with data uncertainty. The Harvest Strategy has been published by the Australian Commonwealth Government as an example of an approved Harvest Strategy and is being implemented as designed. Dr Prince has gone on to extend the SPR-Decision Tree concept to assessing data-poor fisheries in general.

Assessing Traditional Dugong Hunt, Torres Strait

In northern Australia the traditional owners of Torres Strait enjoy a continuing statutory Traditional Right to hunt the dugong (Sirenidae) but data on the hunt are sparse and stock status is uncertain. The project was to synthesise all available information and develop a most likely assessment in the form of interactive colour computer graphics software for interpretation by traditional hunters and their communities. The project involved gathering anecdotal information and assembling a plausible density dependence mechanism for dugong based on reproductive studies over a wide range of densities. The project was granted a privileged glimpse of the deep knowledge of dugong herd behaviour possessed by the Torres Strait hunters. It is hoped that the education provided by the rudimentary assessment in interactive computer software will facilitate local communities improving management and data collection.